Glass bottles have classically been fabricated by employing metal bottle molds in which the glass bottles are formed. The glass bottles are formed in a two stage process. In the first stage, a “gob” of glass is placed into a blank bottle mold and blown into a crude glass shape having a central cavity. The crude glass shape is then transferred to a final blow bottle mold, in which the crude glass shape is blown to its final shape. The technique for blowing glass into such molds is further discussed in an article entitled Auckland Bottle Works—New Zealand, available on the Internet at the URL “http://www.glass.co.nz/NZglassbottles.htm”. The metal bottle molds employed in both of these stages for forming glass bottles are frequently fabricated from cast iron, having a glass contact surface for defining the shape of the glass. While these cast iron bottle molds can, for the most part, withstand the thermal and mechanical stresses which result from the hot glass contacting and flowing over the glass contact surface, there are regions of the bottle molds where the hot glass preferentially degrades the cast iron. This problem is of particular concern with the blank bottle molds, where the temperature of the glass is higher.
The problem of degradation of these regions of the metal bottle molds has, in part, been overcome by providing depressions in these regions, the depressions then being filled with a more durable metal such as a nickel alloy. The depressions can be filled by depositing weld metal into the depressions and thereafter machining the molds to their final contours. Shortcomings of this technique are that it is both time consuming and expensive, as is pointed out in the background of U.S. Pat. No. 4,555,259. The '259 patent teaches a method for fabricating such molds which eliminates some of the problems associated with the welding technique, by casting durable metal inserts into the metal molds. However, to practice the method taught in the '259 patent, both the size of the inserts and the gating system employed to introduce the molten metal into the casting mold must be carefully controlled. Thus, there is a need for a metal bottle mold which can be more easily fabricated and where there is greater freedom in both the size of the inserts which can be incorporated in the mold and the gating system employed to fill the casting mold in which the metal bottle molds are cast.